Causal effect of education on type 2 diabetes: A network Mendelian randomization study

Li-Zhen Liao; Zhi-Chong Chen; Wei-Dong Li; Xiao-Dong Zhuang; Xin-Xue Liao

doi:10.4239/wjd.v12.i3.261

Causal effect of education on type 2 diabetes: A network Mendelian randomization study

World J Diabetes. 2021 Mar 15;12(3):261-277. doi: 10.4239/wjd.v12.i3.261.

Authors

Li-Zhen Liao¹, Zhi-Chong Chen², Wei-Dong Li¹, Xiao-Dong Zhuang³, Xin-Xue Liao⁴

Affiliations

¹ Department ofHealth, Guangdong Pharmaceutical University, Guangzhou 510275, Guangdong Province, China.
² Department of Cardiology, The Sixth Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510080, Guangdong Province, China.
³ Department of Cardiology, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510080, Guangdong Province, China.
⁴ Department of Cardiology, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510080, Guangdong Province, China. liaoxinx@mail.sysu.edu.cn.

Abstract

Background: The causality between education and type 2 diabetes (T2DM) remains unclear.

Aim: To identify the causality between education and T2DM and the potential metabolic risk factors [coronary heart disease (CHD), total cholesterol, low-density lipoprotein, triglycerides (TG), body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), fasting insulin, fasting glucose, and glycated hemoglobin] from summarized genome-wide association study (GWAS) data used a network Mendelian randomization (MR).

Methods: Two-sample MR and network MR were performed to obtain the causality between education-T2DM, education-mediator, and mediator-T2DM. Summary statistics from the Social Science Genetic Association Consortium (discovery data) and Neale Lab consortium (replication data) were used for education and DIAGRAMplusMetabochip for T2DM.

Results: The odds ratio for T2DM was 0.392 (95%CI: 0.263-0.583) per standard deviation increase (3.6 years) in education by the inverse variance weighted method, without heterogeneity or horizontal pleiotropy. Education was genetically associated with CHD, TG, BMI, WC, and WHR in the discovery phase, yet only the results for CHD, BMI, and WC were replicated in the replication data. Moreover, BMI was genetically associated with T2DM.

Conclusion: Short education was found to be associated with an increased T2DM risk. BMI might serve as a potential mediator between them.

Keywords: Body mass index; Coronary heart disease; Education; Genome-wide association study; Mendelian randomization; Type 2 diabetes mellitus.